Break Through: Fieldbus Protocols

Fieldbus Protocols Continue Pushing into Mainstream Process Applications, and Innovative Users Are Forcing Their Network Infrastructures to Evolve Along with Them

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Kinsley adds that the main benefits of using FF and other digital networks at Saudi Aramco's plants are cost and use of advanced features for commissioning and troubleshooting. "We've achieved cost reductions by adopting digital fieldbuses, and these come primarily from reduced requirements for cabling and the footprint of the I/O and marshalling cabinets. We've also seen a reduction in commissioning time for fieldbus-based instruments. This is primarily from the reduced calibration requirements for smart instruments."

Charlie Piper, senior program manager for Invensys Operations Management's ( DCS and control platforms division, reports that users are adapting and learning how best to use fieldbuses more than ever before. "There's a whole revolution going on in how users are hooking up sensors and actuators into their control systems," says Piper. "We used to have politics and hype, but now fieldbus technology is mature enough that people are running with it, and this is driving a lot of the cooperation going on now. In fact, in the past several months, several big oil and gas users told some vendors, who had been fighting against opening up the fieldbus protocols, that the vendors must open them up or the users would go elsewhere. There's still a lot of turmoil, but now it's going in the right direction because it's being pulled by the end users." For example, Invensys' fieldbus system contributed to a successful startup on Saudi Aramco's Shaybah GOSP4 project that began producing oil this past June.

Continuing Cooperation

Most likely, the simplest mathematical formula in digital fieldbus is ECT + FDT + OPC = FDI. Of course, it's a summary of how the EDDL Cooperation Team and the FDT Group partnered with help from the OPC Foundation to form the FDI group.

ECT's steering committee reported in May that its technical team has achieved some important milestones in developing a common solution for FDI. And FDI's project team has worked over the past 18 months to identify use cases encompassing all facets of plant operations from start-up and commissioning to ongoing maintenance activities and plant operations. It also drafted an architecture concept migrating participating technologies to a common device integration standard. ECT reports that results of the FDI project are based on cooperation from suppliers, including ABB, Emerson Process Management, Endress+Hauser, Honeywell, Invensys, Rockwell Automation, Siemens, Smar and Yokogawa, as well as ECT's members.
In addition, the FDI team has performed a complete inventory of use-case analyses and designed a draft for an architecture concept and for functional specifications. The architecture is a client/server structure based on OPC-UA's client/server protocol. This method's field device integration is realized by a "device package" provided by the device supplier containing EDDL components and an optional programmed component for programmed user interfaces. This design will allow complete flexibility to develop customized user interfaces.

"FDI will standardize all EDDL and FDT devices and give them one core for their information model and one core for their data services, and this will mean standard configuration and run-time operations," says Tom Burke, OPC Foundation's executive director. "So any field device will be able to plug in, and any generic application will be able to configure it. A valve is a valve is a valve, independent of its manufacturer. This is bigger than any of us can imagine. It will make our devices just like USB because they now will be instantly recongnized."

The current phase of the FDI project includes development of the detail specifications followed by validation of the specifications by each of the member organizations, which began during the second quarter of 2009. Details of the exact FDI architecture and associated device interface will be unveiled with the release of the final functional specification, currently planned for the summer of 2010.

In addition, Dave Glanzer, Fieldbus Foundation's technology development director, reports that the foundation and ISA have been cooperating since last October on developing a wireless I/O (WIO) backhaul network to help users bring in more remote signals and data from their applications.

Up-Front Engineering is Up and Running

These new levels of cooperation among the fieldbus organizations and their protocols are coming just in time—if not way overdue—for many users and their applications, and gives them some much-needed confidence at a time when nerves are frayed due to recent economic recessions. For instance, now more than ever, ethanol producers must tightly control their plants to produce consistently high yield and minimize energy and raw material consumption. This also means protecting their fieldbus physical layer against short circuits, improper terminations and many other problems.

For example, Abengoa Bioenergy Corp. ( built its 88-million gallons per year (MGY) greenfield ethanol production plant in 2006 in Ravenna, Neb., and commissioned it in February 2007 (Figure 1). To design and install the plant's control system, Abengoa recruited system integrator FeedForward Inc. ( As one of the largest dry-mill ethanol plants in the U.S., its dry-mill process hydrolyzes corn starch into sugar and then ferments it into alcohol. The steps include milling, liquefaction, saccharification, fermentation, distillation, dehydration and denaturing.

To achieve tight plant control at low cost, Abengoa assigned its project team to implement an automation architecture connecting "smart" field instrumentation with diagnostics and troubleshooting information into a distributed control system (DCS) over digital networks. After evaluating several solutions for plant enterprise automation, Abengoa chose Yokogawa's Corp. of America's ( Centum CS3000 DCS to enable distributed control throughout the plant. It distributes control strategies to field instruments, enables flexible device networking and allows free access to processes and devices via system software. Yokogawa DCS employs Foundation fieldbus' H1 for use with analog devices, and then uses AS-interface ( with a Profibus DP gateway for all motor control centers (MCCs).

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